Determine list of event handlers bound to event

In short, you’re not meant to do this – but for debugging purposes…

An event is often backed by a private field – but not with controls; they use the EventHandlerList approach. You would have to access the form’s protected Events member, looking for the object mapped to the (private) EVENT_FORMCLOSING object.

Once you have the FormClosingEventHandler, GetInvocationList should do the job.

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using System;
using System.ComponentModel;
using System.Reflection;
using System.Windows.Forms;
class MyForm : Form
{
    public MyForm()
    { // assume we don't know this...
        Name = "My Form";
        FormClosing += Foo;
        FormClosing += Bar;
    }

    void Foo(object sender, FormClosingEventArgs e) { }
    void Bar(object sender, FormClosingEventArgs e) { }

    static void Main()
    {
        Form form = new MyForm();
        EventHandlerList events = (EventHandlerList)typeof(Component)
            .GetProperty("Events", BindingFlags.NonPublic | BindingFlags.Instance)
            .GetValue(form, null);
        object key = typeof(Form)
            .GetField("EVENT_FORMCLOSING", BindingFlags.NonPublic | BindingFlags.Static)
            .GetValue(null);

        Delegate handlers = events[key];
        foreach (Delegate handler in handlers.GetInvocationList())
        {
            MethodInfo method = handler.Method;
            string name = handler.Target == null ? "" : handler.Target.ToString();
            if (handler.Target is Control) name = ((Control)handler.Target).Name;
            Console.WriteLine(name + "; " + method.DeclaringType.Name + "." + method.Name);
        }
    }
}